Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$141.95	7.695%	$152.8731	$152.87	$152.85	$152.90
Purchase #2	$13.99	9.534%	$15.3238	$15.32	$15.30	$15.30
Purchase #3	$83.35	5.574%	$87.9959	$88.00	$88.00	$88.00
Purchase #4	$90.72	8.225%	$98.1817	$98.18	$98.20	$98.20
Purchase #5	$50.89	13.725%	$57.8747	$57.87	$57.85	$57.90
Purchase #6	$153.83	7.458%	$165.3026	$165.30	$165.30	$165.30
Purchase #7	$157.41	5.416%	$165.9353	$165.94	$165.95	$165.90
7 purchase totals =	$692.14		$743.4871	$743.48	$743.45	$743.50